Nissan is very strong and successful brand in Dubai just after Toyota which leads the undisputed no.1 place since forever. Just to answer your questions: Nissan cars survive extremely well in Dubai heat or in fact UAE heat as sometimes Abu Dhabi is hotter than Dubai.Nissan maintenance is very competitive and almost at the lowest level compared to all other Japanese brands. Below list is general maintenance cost comparison between Japanese brands.Toyota (Most cheapest)NissanMazdaHondaMitsubishi (Most expensive)For Nissan spare parts: Same as maintenance chart aboveRemember to buy car from private deal than the used cars dealer, as in Dubai there are plenty of free used car classifieds website, newspaper and car magazines that you can search and get good deals on wheels. Only if you are not in rush, as you might need to spend few days with your friends or taxi in arranging few viewing, but trust me its worth it.